Electrical controlling system.



I; G. ROBERTS.

ELECTRICAL CONTROLLING SYSTEM.

APPLICATION FILED DECIB. I914.

Patnted Feb, 20, 1917.

9Q l s F 32 2 IW 4 I Mm a A33: Q IMW u E I w. NQ

.; UNITED STATES PATENT OFFICE.

OHN G. ROBERTS,- or nouns FERRY, NEW YORK, nssxcNOB, BY Mnsunnssrenmnnrs,

description.

'ro WESTERN ELECTRIC: COMPANY, INCORP ORATED, A CORPORATION OF NEW YORK.

I nnncrrRican ccNTRoLLINc SYSTEM.

. Application filed December a,

To all whom it may concern:

Be it known that I, JOHN G. Ronnnrs,

'a citizen of the United States, residing at Dobbs Perry,

in the county of VVestchester New York, have invented cerusefulImprovements in Elecand State of tain new and trical ControllingSystems, of which the following is a full, clear, concise, and exactThis invention relates to electrical controlling systems and isparticularly adapted -.for multi-ollice telephone exchange systems.

In such systems it is desirable to prov de connections betweensubscribers lines which terminate at difl'erent oilices by means oftwo-wire interoffice trunks, and it is 'desirable also to use the twowires of the trunk k for controllingthe signals and switchesi'n volvedin an established connection. It is controlling circuits between theoiiices whi,ch-=--- depend upon a ground return path between theofiices. In certain systems, such as semiautomatic exchanges providing'"operators- -answering equipment and automatic switches furthermoredesirable to avoid the use of under the control of operators senders forcompleting connections to wanted lines, the wanted subscribers shouldhave control of an operators supervisory signal, and the operator shouldhave control of the release of the automatic switches after the circuitis established. It is also desirable that the. operator have controlofthe ringingequip ment, in order to rering on the calledsubscribers..;line,withoutithe necessity of first restorinfitheconnection and building it up again. Because of the long distancesbetween oflice's and high cost of trunk con-- ductors, it isfusual toform the interoffice trunk conductors into a telephonic link and tounite thislink inductively with the line circuits ofi the calling andcalled subscribers, current to each line being supplied by battery atthe oiiice where the line terminates. 1 l

It is'the object'ot' this invention to pro- .vide for the varioussignaling and switch controlling functions, required in an establishedinteroflice connection in such a system, by means of a single loopcontrolling circuit extending over the same two wires which constitutethe telephonic trunk link. in accordance, the invention provides thatthe trunk loop be maintained as a closed controlling circuit with asource of current Specification of Letters Patent.

Patented Feb. 20, 1917;. 1914'. Serial in. 876,083.

other common return path at the distant end. A succession of temporarychanges in current produced preferably by momentary interruptions at theincoming end eflect the supervisory signalat the'operators end, by

alternately displaying and efiacing it. These current changes arepreferably of different kind, such as those caused by a shortinterruption and one of longer duration, the short ones, being say ofone-tenth of a second and the longer ones say of four-tenths of second,and means is provided whereby the called substation switch, in beingclosed and opened, effects the short and long current changesrespectively, in the trunk loop.

The control in the other direction, that is to say, from the operatorsend of the trunk to the apparatus at the incoming" end, is

effected by similar current changes in the same circuit. Thus therestarting of an automatic ringing apparatus may be effected by a shortinterruption in the trunk circuit at the operators end, and the releaseof the automatic switch or switches at the incoming end, whether thecalled line circuit is,

at the moment open or closed, may be efiected by a prolongedinterruptionor opening of the trunk circuit at the operators end.

,This invention iiill be more fully understood by referenc to theaccompanyingdrawings wherein is illustrated a system of circuits andapparatus operable in accordanoe with the foregoing general statement.Two subscribers stations, 1,2are, shown In a connection assumed to havebeen established through a two-wire interofiice trunk link with thecircuits and apparatus Involved therein. A. plug and jack switch 3unites the calling line with an operators connecting circuit, which isdivided as is usual into inductive sections by windings 4, 5 and 6, 7 ofa repeating coil. The trunk end of this connecting circuit is unitedwith atwo-wire interoiiice trunk line 8, 9 by means of the contacts 10and 11, say of an automatic switch. The trunk is divided at its incomingend into inductive sections by the windings 12, 13 and 14, 15 of.another repeating coil. A battery 16, at the outgoing end suppliescurrent to the calling line and to the trunk line loop. A. battery 17;at the incoming end supplies current to the called line. A condenser 18,at the outgoing end completes the trunk loop as a telephonic link in thesystem of circuits between the two stations. Contacts 19, 20, which mayalso be assumed to be of an automatic switch, unite the called linesection of the trunk with the called line.

T he system of circuits is shown in its con dition just following theoperation of setting up the automatic switches and preceding the closureat certain contacts in the connecting circuit of the trunk loop betweenthe oliices. are provided for controlling the operation of the circuitsassociated with the two auto matic switches, indicated in the diagram bythe contacts 10-11 and 19-20, respectively. To avoid unnecessarycomplication in a full disclosure of the invention, much of theapparatus involved in the preceding steps in the operation of thesystem, that is to say, preceding the setting up of the connectionsshown in the diagram, is omitted. it is therefore assumed that inresponse to a call from substation 1, the operator had established aconnection at the plug and spring jack switch 3, had inquired of thecalling subscriber the number of the party wanted, and had manipulatedautomatic switch sending apparatus or in some other mannerv had causedthe connection. to be set up to the called station 2. The switches usedin establishing this connection may be either manual or automatic. andthe system as a whole may be manual. full automatic or semi-autonmtic,without departing from the invention broadly, and the number of switchesused in making a single connection is immaterial. It is assumcdthat thesequence switch 21 had, by successive stages, reached a resting position11, and sequence switch a resting position '13. The succeeding restingpositions of the sequence switch 21. involved in the operation to bedescribed, are follows: 1'-lringing; 16- talking and1S--switch-restoring. The succeeding resting positions of the sequenceswitch are: 16 talking and 1S-switchrestoring. The master switchcontacts 105 and 106 are arranged so that the sequence switches 21 and22, after having been moved out of one resting position, may bekeptmoving until the next resting position is reached.

Sequence switch 21 is moved out ofposition 11 by the momentary closureof a contact 23, which closure may be effected in any desired manner,prcferal' ly automatically upon the establishment ofthe connection shownin the drawing. In its advance to the ringing position 14, the sequenceswitch 21 closes at contacts 24 and 25 the trunk Sequence switches 21and 22 28, 29, 30, 31, 32, s, 10, 24, 6, ground. A I

supervisory relay 26 at the operators end of the trunk, and a trunkrelay 33 at the incoming end of the trunk are energized. The formercloses a circuit ground, 31, 35, 36, battery. The magnets and 36, withtheir armatures, constitute an interlocking switch, and when bothmagnets are energized in the circuit thus traced, the armature 37 ofmagnet 35 being a little quicker than the armature 38 of magnet 36,prevents the latter from moving forward. A point extension 39 of thearmature 37 engages the inside edge of the pointed end 40 of thearmature 38. The trunk relay 33 acts to close a circuit for the motormagnet of the sequence switch 22, as follows: ground, 41, 42, 22,battery, and this sequence switch moves out of position 13 into thetalking position 16. In passing position 14, sequence switch 22 closes acircuit as follows: ground, 43, 44, -15, battery. A by-path for contact45 isprovided in this circuit at the contact 46 of the relay 43 whenthe' latter is energized, so that as the sequence switch 22 reachesposition 16, the circuit just traced becomes ground, 43, 44, -16,battery.

The ringing of the called subscribers bell may be effected automaticallyat this time as follows: A relay 4?, held up by contact 102 in positions13 and 14 of the sequence switch 22 is released as the sequence switchleaves position 14, closing a ground connection at contact 48 for alocal ringing control circuit. Relay 4:? was energized in position 12 ofsequence switch 22 over a circuit, from grounded battery, winding ofrelay 47, upper contact of 102, to ground. The contact 48 remainsclosedduring the subsequent operations to be described. hen the se quenceswitch 22 moves into position 16, this local ringing control circuit isclosed through the ringing relay 51 as follows:

ground, 48, 49, 50, 51., 52, 44-, 46, battery. Ringing generatorcurrentis now applied to the called line over a circuit as follows:

generator, 53, 54, 55, 56, 57, 20, 2, 19, 58, 59, ground. Current flowsfrom generator 53 It does operate to the increased current inithetelephone line, and then opens at contact 49 a shunt about the lockingrelay "'60. The latter in turn closes at contact 61 a-shuntabout therelay Belay 51 therefore reacts, opening the circuit of the ringinggenerator just traced, and closes the battery circuit to the supervisory7 follows: ground, 65,

called line.

67 in turn closes two of an impulse relay 6-) as follows: ground,

68, 69,. battery and ground, 70, 71, 72, battery. Relays 71 and 72 areenergized, the

' former opening at contact 66 the circuit of subscriber at station 2therelay 67. The latter is adjusted to release a' brief moment after. itis energized,

say in about one-tenthof a second, so that the impulse relay 69 is givenonly amomentary impulse of current. I

his momentary impulse of current in relay 69 causes a momentaryinterruption at contact 28 in the trunk circuit. In order to avoid therelease of the trunk relay 33 while the trunk circuit is thusinterrupted, a circuit battery, 73, 74, ground, is closed atthe sametime, this circuit including a second winding 7% of the trunk relay 33.The energization of. relay 71 closes a locking circuit-battery, 72, 71,75, 65, ground, which maintains relays 71 and 72 energized while thesupervisory controlrelay 62 is energized. The momentary interruption ofcurrent in the trunk circuit thus occurring when the answer the call,causes a momentary reaction of the supervisory relay 26 at the operatorsend of the trunl. This momentarily opens the circuit through magnets 35and 36, but

1 the magnet 36 is equipped with a copper colc1rcuitground, 38, 76, 77

' lighting of the ringing lamp lar by reason of which it continues toattractits armature 38 after the circuit of its winding is interrupted.But the armature 37 of magnet 35 releases quickly, sothat armature 38has time in which to move forward while the extension 39 is lifted. Thelocal circuit of the magnets 35 and 36 is however quickly reclosedby thereiinergization of relhy 26, so

that armature 37 of magnet'35 is again attracted. The projection 39 thenengages the outside edge of the pointed end 40, of the armature 38.

The sequence switch 21 is at this moment in ringing position 14, and theoperation just stated results in the closure of a local 21, battery,which causes the sequence switch to move out of position 1% into talkingposition 16. 7

While sequence switch 21 was rcstingin position" 14, there had'beenclosed a circuit,

battery, 78, 79, 80, ground, which causedthe 79. The move- I ment of thesequence switch 21 to position 16 opens this ringing lamp circuit,notifying the opermtor of the called subscribers response, andjcloses adivided (-ircuit,,as follows: battery, 7 8 thence in one path by way of81, 82, 76, 38 to groundand in another path by way of the supervisorylamp signal closes his line to.

83 and 84 to ground. In this divided circuit, the supervisory lampsignal 83 is brought under control of the contact 76 of the magnet36 andthereby under the control of the supervisory relay 26. At this time itis the contact 76.

shunted by resistance 81 in the path through Subsequent openings andclosings of the called subseribers circuit which may be repeatedindefinitely at the subscribers switch hook, result in the lighting andeifacing of the supervisory signal 83 in the following manner. Considerfirst the and the opening at contact 65 of the then existing circuitthrough relays 71, 72. Relay 71 releases quickly, say. in one-tenth of asecond and relay 72 slowly, the latter in about four-tenths of a second,after the current is removed from its winding. This results in animpulse of current of about four tenths of a second in the winding ofrelay 69, the circuit being as follows: ground, 85, 86, 69, battery. Thetrunk loop is thus again interrupted at contact 28.

opening of the subscrlberscircuit. This results in the re- .action ofthe supervisory control relay 62,

This time the interruption is of'longer" duration,'say four-tenthsinstead of oneup his receiver. A subsequent closing of the called linecircuit operates to close contact 76 and effaces the signal 83, theoperation being the same as previously described.

In the event that the called subscriber has responded and replaced hisreceiver, and then the calling subscriber wishes to have the operatorrecall on the called line, the operator may restart the automaticringingagain closed at they 35 again locks the apparatus by momentarilydepressing a rering key 87. The operation is as follo'wsi on pushingdown the key 87 there is closed a contact 88, and a contact 89, thelatterin a, circuit ground, 89, 90, battery, which includes a relay 90.The relay closes contacts 104. and 103 and opens contact 27, establishing the following circuits: ground, 103, 2c, 7, 1s; and battery,88,104, 25,11, 9, 28, 29, 30,31, 32, 8, 1O, 21, ll, ground. WVhenpressure is removed from t e key, contacts 88 and 89 are opened, andrelay 90 which is adjusted to release slowly, say in about onetenth of asecond, holds contact 27 open for that period and thus lreeps the trunkloop v through the locking relay 6U. Ihe latter slay reacts, opening atcontact 61 the shunt alt-out relay 51, and closing at contact 50 theshunt about itself. Relay l3, however, being of the slow release type,maintains its contacts to closed and its contact 91 open. Contact 44 ofthe trunk relay 33 being quickly reclosed, reestahlishes the circuitthrough relay 43 so that this relay does not reset. This contact alsoreestablishes the local ringing control circuit and again energizes theringing relay 51, which again connects the ringing generator 53 in thecircuit of the called line. The subscribers bell is then rung until heresponds again or untii the operator proceeds to disconnect in the tunerpresently to be stated.

Disconnectionot the lines may be effected under either c in of thecircuit of the called line, that ,0 say, Whether the receiver is on orof? the hook at the called station. Under either'condition the trunkloop is closed through the Winding 31 of the trunk relay 33. In asemi-automatic system, such as shown herein, the disconnect operationmay be started by the operator removing the plug from the spring jack ofthe calling line. lhis act breaks a circuit at contact 92 of the plugand spring jack switch 3, in which is ncluded a cord relay 93 andacut-ofi relay 94. Ihe reaction of the cord relay 93 opens batterycircuit for the calling supervisory signal 91, and closes at contact 96a circuit, battery, 21, 95, 96, ground, which cau'ses the sequenceswitch 21 to move out of the talking position 16 into theswimlrrestoring position 18, wherein there is closed a circuit, battery,97, 98, ground, which includes'pa restoring magnet 97 for the automaticswitch that had previously established the trunk connections at contactsand 11. As the sequence switch 21 moves out of position 16 it opens atcontacts 2i and the trunk loop. Trunk relay 33 thereupon reacts, and asthe openingin this circuit is prolonged instead of being momentary as inthe case of reringing,

relay 43 has time to react and to close a Ail-l,

circuit, ground, 99, 91, 100, battery. This circuit includes the motormagnet of the sequence switch 22 which thereupon moves from its talkingposition 16 to its restoring position 18 wherein is closed a. circuit,ground, 101, 102 battery, which inclndes'a restoring magnet 110 for theauto matic switch that had previously established ing 31 of trunk relay33 mo 2. In a telephone exchange system, the I combination with a trunk,and a line circuit inductively united, of a supervisory signal, a switchfor opening and closing the hue circuit, means responsive upon bothclosing and opening the line circuit for producing momentary currentchanges of like character in the trunk circuit, and means responsiveupon successive current changes for alternately displaying and eilacingsaid supervisory signal.

3. In a telephone exchange system, the

combination with a trunk and a line circuit inductively united, of asupervisory signal, a switch for opening and closing. the line circuit,means for producing momentary current changes of like character in. the

.trunk circuit responsive upon both closing and opening of the linecircuit by said switch, and means responsive to the differout currentchanges for efl'acmg and displaying respectively said supervisorysignal.

t. In a telephone exchange system, the combination with a trunk and aline circuit inductively unit-ed, of a supervisory signal, a switch foropening and closing the line circuit, means for producing momentarycurrent changes in the trunk circuit responsive upon both closing andopening of the line circuit, said current changes being of likecharacter but differing in duration, and means responsive to thedifierent current changes for efi'acirig and displaying respectivelysaid supervisory signal.

5. In a telephone exchange system, the combination with a trunk and aline circuit inductively united, of a supervisory signal, a switch foropening and closing the line circuit, means for producing momentarycurrent changes of short and of longer duration in the trunk circuitupon the closing and opening respectively of the line circuit, and meansresponsive to such current changes for controlling said supervisorysignal.

6. In a telephone exchange system, the combination with a trunk and aline circuit inductively united, of a supervisory signal at one end ofsaid trunk, an automatic ringing apparatus and a switch controllingmagnet at the other end of said trunk, a plurality of currentinterrupting switches 111 said trunk circuit, means controlled by asuccession of, momentary interruptions at one end of said trunkcircuitfor controlling said supervisory signal, means controlled by a momentaryinterruption at the other end of said trunk circuit for controlling saidautomatic ringing apparatus, and means controlled by a prolongedinterruption in said trunk circuit for operating said switch controllingmagnet.

7. In a telephone exchange system, a trunk line forming a combinedtelephonic link and a controlling circuit,-means for producingn'unnentary current changes in said circuit, a signaling device to becontrolled over said circuit, and means variably responsive to currentchanges of varying duration for-alternately displaying and efi'acingsaid signal. a

8. In a telephone exchange system, the combination with a trunk and .aline circuit inductively united, of a supervisory signal,

a switch for opening and closing a line circuit, n1eans responsive uponboth closing and opening the line circuit for producing momentarycurrent changes of varying duration in the trunk circuit, and meansvariably responsive to such current changes for alternately displayingand'efia'cing said supervisory signal.

9. In a. telephone exchange system, the combination with" a trunk and aline circuit inductively united of a supervisory signal,

means variably responsive to such curre'ntchanges for eifacing anddisplaying respectively, said supervisory signal.

In witness whereof, I hereunto subscribemy name this 7th day ofDecember, A. D.

JOHN G. ROBERTS. VVitnes'se's:

E. EDLER, F. FEISTER.

